PLATE LVIII. 
Bigs: isto” -SasONCOGHRAS GEV CUM ELE Ne vctersts cpssrrers afnrarn a) a telerctereteiole cya alate tie taie aiataiarerevuyel teleteteeslatorestera 799 
Bares 2s} Views of the body-chamber and a few air-chambers; showing the form of the 
aperture and contraction of the conch. 
3a Outline of the septa. From the Trenton limestone, Minneapolis. 
Migs. 4° to -64:\ONCOGERAS PANDION: SEAMS iro crezs crevasesarelojerovnre ines caterer tetetevete <a sare cre eicye.aroterals cereale 799 
4 Side view of an internal cast retaining the body-chamber and its apertural edge. 
5; 6 Ventral and lateral views, showing the course of the septa. 
6a Outline of the septa, showing the ventral position of the sipho. Janesville, Wis. 
MICE: oi, (60) (9S ONCOGERAS CARVER IG ISD sl OMe eircrteeiotecisioiels asic telsiore stevonieiaeieinetatetcisieloreeeate eit 799 
Dorsal, lateral and ventral views of an internal cast; showing the lateral com- 
pression of the conch, the slight constriction of the body-chamber and the form 
of the aperture. Trenton limestone, Minneapolis, Minn. 
igs Olan li) ONCOCERAS SEX1TGUUME PEI Tn Oi yore rayerele eis evade olapote lererate late okerere lave steps tareietetel ote leteketetetste aketeteretisie 798 
Two imperfect internal casts. From the Galena horizon at Fountain, Minn. 
Figs. 12 to 15a CYRTOCERAS FEATHERSTONHAUGHI, SP. MOV.....2.2.0202ececnccconeses secssveces 807 
12, 13,14, 15 Lateral, dorsal and ventral views; showing the characters of the species. 
15a Outline of a septum; showing the ventral position of the sipho. Cannon Falls, 
Minnesota. 
Figs. 16 to 18) ONCOCERA'S MINNESOTENSH; SP) NOV: cle e cet eiiees sec enle oicilecirlolcle slejsintelalsini= atelelia 798 
16, 17, 18 Dorsal, ventral and lateral views of a specimen leading to the body-chamber; 
showing the longitudinal ridges of the surface. 
18a, 18b Outlines of septa, showing the ventral position of the sipho. From the Galena 
beds at Lime City, Minn. 
